Oxanilide U-V absorbers

ABSTRACT

Oxalic acid diarylamides are described as useful monomers and comonomers in the polymerization of polycarbonates. The resin products resist degradation by ultra-violet light radiation. They can also be incorporated as comonomer or monomer in the polyester, polyester, polyether, polyethersulfone resins. They can also be used as UV stabilizers in the aforemetioned systems.

This is a divisional of application serial no. 08/783,598 filed on Jan.13, 1997 now U.S. Pat. No. 5,698,732.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to oxalic acid diarylamides and more particularlyto oxalic acid bis-hydroxydiarylamides and their use in absorbingultra-violet light.

2. Brief Description of Related Art

Oxanildes based on benzene and substituted benzenes are known to beuseful as ultra-violet light absorbing compounds; see for example thedescription given in U.S. Pat. No. 4,618,638. The patent describes theseoxanildes as useful monomeric compounds for incorporation into a varietyof polymer systems, including polycarbonates, to stabilize them againstdegradation by exposure to ultra-violet radiation.

In a similar vein, the U.S. Pat. No. 3,906,033 describes oxalic aciddiarylamides which are useful as ultra-violet absorbing light compounds.

SUMMARY OF THE INVENTION

The invention comprises a compound of the formula: ##STR1## wherein n isan integer of 0 to 1; x is an integer of 0 to 4; R represents amonovalent moiety of the formula: ##STR2## wherein R₁ is alkyl or aryl;and R₂ represents alkylene.

The term "alkyl" as used herein means the monovalent moiety obtainedupon removal of a hydrogen atom from a parent alkane. Representative ofalkyl are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,nonyl, undecyl, decyl and dodecyl. Preferred alkyl have from 1 to 12carbon atoms, inclusive.

The term "alkylene" as used herein means the divalent moiety obtained onremoval of two hydrogen atoms, each from a parent hydrocarbon alkane andinclude, for example, methylene, ethylene, propylene, butylene,pentylene, heptylene, octylene and isomeric or alicyclic forms thereof,preferably having from 1 to 8 carbon atoms.

The compounds of formula (I) described above wherein R represents themonovalent moiety of formula (II) are useful as intermediate compoundsto prepare the compounds (I) wherein R represents the monovalent moietyof formula (III) and as chain stoppers in condensation polymerizations.The compounds of formula (I) given above wherein R is the monovalentmoiety of formulas (III) is useful as an ultra-light absorbing compoundto protect organic materials, more particularly polymers, copolymers andblends thereof from the deleterious effect of ultra-violet rays. Due tothe presence of two independent hydroxyl groups, these compounds areconceptually similar to Bisphenol A. They can be used as monomer andcomonomer in the preparation of polymers such as polycarbonates,polyesters, polyethersulfone, polyethers, polyurethanes and some coatingcomponents of acrylic and polyester enamels that are cross linked withhydroxymethyl-melamine and/or alkoxymethyl melamine curing agents.Furthermore, with their high molecular weight and their hydroxylanchors, the compounds of the present invention are resistant tovolatilization and exudation from resin compositions during processingand/or weathering.

The compound (I) of the invention, unlike aniline derivatives basedoxanilide, absorb at higher wavelength without any detrimental effectson their absorbtivity. Contrary to derivatives of aminophenol, theformation of the oxanilide functionality does not affect the reactivityof the hydroxyl group, they are not in the same phenyl ring and areseparated by an alkylene or alicyclic bridge.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The compounds (I) of the invention may be prepared by reaction ofstoichiometric proportions of a hydroxyaminodiphenylalkane of theformula (IV) with a dialkyl oxalate (V) according to the schematicformula: ##STR3##

The compounds of formula (IV) are generally well known as are methods oftheir preparation; see for example the descriptions given inOffenlegungsschrift 29 45 179 and Auslegeschrift 1 251 334.

The compounds of formula (V) are also generally well known as aremethods for their preparation. Representative of known compounds (V) aredimethyl oxalate, diethyl oxalate, dipropyl oxalate, dibutyl oxalate,dientyl oxalate oxalic acid, and oxalyl dichloride. ##STR4##

The reaction of the compounds (IV) with compounds (V) proceeds at refluxtemperatures and ambient pressures in the presence of a lewis acid andan inert solvent. The term "inert solvent" as used herein means asolvent for the reactants which does not enter into or adversely affectthe desired course of the reaction. Representative of inert solvents arebenzene, toluene, cyclohexane; preferably halogenated aromatic solventssuch as dichlorobenzene.

Upon completion of the reaction, the desired product (I) may beseparated from the reaction mixture by conventional means such asdistillation, precipitation and filtration.

Although not necessary, it may be advantageous to carry out thepreparation of the compounds (I) of the invention under an inertatmosphere, such as a nitrogen gas blanket.

The invention will be better understood with reference to the followingexamples, which are presented for purposes of illustration rather thanfor limitation and set forth the best mode contemplated for carrying outthe invention.

EXAMPLE 1 ##STR5##

A 3 liter round bottom flask equipped with an overhead stirrer, acondenser a Dean Stark trap and a thermometer was charged with:

113.64 grams of 2-(4-aminophenyl)-2-(4'-hydroxyphenyl) propane (0.5mole);

36.53 grams of diethyl oxalate (0.25 mole);

20 grams of boric acid; and

600 ml of ortho dichlorobenzene.

The resulting mixture was heated to a temperature of 177° C. for 12hours and refluxed at 185° C. for 6 hours. During the hold at 175° C.,ethanol was collected in the trap. Afterward, the reaction mixture wasallowed to cool to 120° C., then poured into an ice cooled solution oftoluene. The product (VI) precipitated out. It was collected byfiltration, washed with water and oven dried at 120° C. The product wasrecrystallized in toluene. MP: 234°-235° C. The structure was confirmedby ¹ H and ¹³ C NMR. Yield: 80%.

EXAMPLE 2 ##STR6##

A round bottom flask equipped with a condenser, a dean stark trap, anoverhead stirrer and a thermometer was charged with:

700 grams of diethyl oxalate;

60 grams of boric acid; and

117 grams of 2,2-(4-aminophenyl)-(4'-hydroxyphenyl) propane.

The resulting mixture was heated and stirred at a temperature of 150° C.for 6 hours. After draining away, ethanol trapped in the Dean-Stark, thereaction mixture was refluxed for 6 hours at 185° C. Thereafter, nearly400 ml of diethyl oxalate was distilled off. The remainder of thereaction mixture was allowed to cool to 120° C. and subsequently pouredin an ice cooled beaker containing 1500 ml of toluene. The product (VII)precipitated out, was collected by filtration and was finallyrecrystallized from toluene. Spectroscopic data are consistent with theassigned structure (VII). Yield 95%.

EXAMPLE 3 ##STR7##

A round bottom flask equipped with an overhead stirrer, a condenser, aDean Stark trap and a thermometer was charged with:

500 ml of ortho dichlorobenzene;

20 grams of boric acid;

32.7 grams of the compound prepared in Example 2, supra.; and

23 grams of 2,2-(4-aminopheny)(4'-hydroxyphenyl) propane.

The resulting mixture, with stirring, was heated to a temperature 175°C. for 12 hours. After emptying the trap, the reaction mixture wasrefluxed at 185° C. for an additional 6 hours. Thereafter it was allowedto cool to 120° C. and poured in a cold solution of toluene. The product(VI) precipitated out, was collected by filtration and dried at 120° C.The product (VI) can also be recovered by cooling the reaction mixtureat room temperature with vigorous stirring. Recrystallization fromtoluene afforded the pure product whose spectroscopic data are identicalto those of the product prepared in Example 1, supra.

The compounds (I) of the invention absorb ultra-violet light within theregion of from about 285 to 320 mμ. They can be incorporated intopolycarbonate polymer systems, replacing from 1 to 10 percent by weightof bisphenol-A, following the procedure for example of U.S. Pat. No.3,989,672 to obtain polycarbonate resin resistant to degradation byexposure to ultra-violet light, or they can be added in the bulk of anyother polymer as additives.

What is claimed:
 1. A compound of the formula: ##STR8## wherein n is an integer of 0 to 1; x is an integer of 0 to 4; represents a monovalent moiety of the formula: ##STR9## wherein R₁ is alkyl or aryl; and R₂ represents alkylene.
 2. A compound according to claim 1 wherein R represents the moiety of formula (II).
 3. A compound according to claim 1 wherein R represents the moiety of formula (III).
 4. A compound according to claim 1 wherein n is O.
 5. The compound of formula: ##STR10## wherein R₂ represents alkylene; Ry1 and Ry2 represent alkyl, alkoxy or alkylaryl; and Ry'1 and Ry'2 represents Br, C1, alkyl, alkoxy or alkyl aryl. 